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A122492 Semiprimes n such that 1+2n+3n^2 is also semiprime. 0
4, 6, 9, 10, 15, 21, 22, 33, 35, 57, 69, 77, 82, 86, 95, 111, 123, 134, 143, 146, 161, 183, 202, 203, 209, 218, 219, 221, 249, 262, 267, 298, 299, 302, 314, 321, 323, 326, 329, 334, 335, 339, 341, 417, 422, 446, 454, 471, 489, 515, 543, 551, 554, 562, 566, 573 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Cf. A086285 (Numbers n such that 1+2n+3n^2 is prime).

EXAMPLE

n=4=2*2 (semiprime) is OK because 1+2n+3n^2=57=3*19 (semiprime), etc.

CROSSREFS

Cf. A086285.

Sequence in context: A084662 A137167 A181564 * A178378 A133234 A111206

Adjacent sequences:  A122489 A122490 A122491 * A122493 A122494 A122495

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Oct 20 2006

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Last modified February 17 04:26 EST 2012. Contains 205978 sequences.